The isocenter in x-ray imaging is the space through which the central ray of the radiation beams passes.
The CT isocenter is defined by intersection of the gantry axis of rotation. In case of a cylindrical CT type, the isocenter is at the center of the gantry bore.
In radiation oncology the isocenter is defined by the beam centerline of a medical accelerator or cobalt unit. Typically, the isocenter is located 1 m from the radiation source.

The lateromedial view of a mammogram is performed with a 90° angulated x-ray beam directed from the lateral to the medial breast. For a lateromedial oblique view, the x-ray beam is directed from the lower-outer to the upper-inner part of the breast (the exact reverse of the mediolateral oblique view). These views improve the visualization of medial breast tissue (also called true reverse oblique).

Air KERMA (Kinetic Energy Released per unit MAss of air) measures the amount of radiation energy in air, unit is J/kg. This include the initial kinetic energy of the primary ionizing particles such as photoelectrons, Compton electrons, positron//negatron pairs from photon radiation, and scattered nuclei from fast neutrons, when for example air is irradiated by an x-ray beam. J/kg (gray) is also the unit of the radiation quantity 'Absorbed Dose'.

The bisecting angle technique (or bisect angle geometry) is used for radiographic examinations of the teeth. The central axis of the x-ray beam is positioned at right angles to a plane determined by bisecting the angle formed by the long axis of the teeth being imaged, and the plane in which the image receptor is positioned behind the teeth.

See also Bitewing Radiograph.

(B) The Bucky factor is the ratio of x-rays arriving at the grid (incident radiation), and those being transmitted through the grid. The Bucky factor describes how much the output of the x-ray tube must be increased in order to compensate for the removal of incident radiation by a grid.
B = incident radiation / transmitted radiation
For example, if for every two x-rays impinging the grid, only one will pass through, then the grid has a Bucky factor of two and the intensity of the x-ray beam must be doubled.